Electronic devices known as information terminals, typically cellular phones and personal digital assistants (PDAs), generally have an operating part for inputting and transmitting/receiving data information and a screen display portion for displaying the data information as characters or images.
A small-screen display portion is preferred in view of the portability of the electronic devices while a larger-screen display portion is preferred in view of the ease with which the content displayed can be viewed.
Recently, electronic devices with various functions, including a phone function and receiver functions for email, the Internet, and television broadcasting, have been devised. Accordingly, there is an increasing need for providing both the convenience of being small (portability) and the display of larger screens and screens with different sizes.
Examples of known electronic devices produced with consideration for portability and the size of a screen display portion are disclosed in Patent Documents 1 and 2 described below.
According to a technique disclosed in Japanese Unexamined Patent Application Publication No. 8-194590, a portrait-oriented screen display portion can be selectively used in either portrait or landscape orientation, and the touch panel area of the screen changes depending on whether the screen is portrait-oriented or landscape-oriented.
According to a technique disclosed in Japanese Unexamined Patent Application Publication No. 2000-184026, left and right halves of a device that opens laterally have separate screen display portions which are combined to form a single, large-screen display portion when they are opened laterally.
According to the technique disclosed in Patent Document 1, the screen display portion can be provided on a cellular phone with its portability maintained. The screen display portion, however, cannot provide a large screen because its own size is fixed and the size of image displayed changes depending on whether the screen is portrait-oriented or landscape-oriented. If, on the other hand, the screen display portion is provided with a large screen in advance, it cannot provide sufficient portability.
According to the technique disclosed in Patent Document 2, on the other hand, the single, large-screen display portion composed of the left and right separate portions has good visibility when used as a screen display portion for television or the Internet.
This device, however, has the drawback of poor usability because it opens laterally, rather than longitudinally. When the device is closed and held in one hand, for example, the device is difficult to open laterally while firmly holding it in only one hand because of the structure of a human hand.
If, additionally, the device is used as a cellular phone, the device cannot be held using the back of the hand, unlike devices that open longitudinally. Unfortunately, therefore, an operating part provided on either left or right surface of the device is difficult to operate quickly with only the thumb.